The present invention relates to resistive gridded drop glass located at the rear of a motor vehicle, and more particularly to an electrical connection mechanism therefor.
One problem associated with driving motor vehicles under adverse weather conditions relates to the potential for ice, snow and/or fog obscuring vision through the rear glass. One effective solution to this problem is the application of a resistive grid which, when electrically powered, serves to heat the glass and thereby cause ice, snow and/or fog to dissipate. Examples of resistive grid systems are found in U.S. Pat. Nos. 4,552,611 and 4,244,774.
An issue that arises with resistive grids is the wiring connection with respect to the motor vehicle electrical system. Generally, the resistive grid is composed of a plurality of horizontal heater bars connected to a vertical bus bar at either end thereof. The bus bars are each equipped with a connector for interfacing with the motor vehicle electrical system, one bus bar connecting to ground, the other to the positive voltage of the system. An example of an electrical connection for a hatchback type motor vehicle having a resistive gridded rear glass described in U.S. Pat. No. 4,997,396.
A problem which remains in the art of motor vehicle resistive gridded glass, is providing an electrical connection to the resistive grid of a rear drop glass (that is, a rear glass which moves up and down relative to the tailgate). In this regard, it would be most beneficial if somehow the electrical connection could be achieved without the necessity of flexing of a wiring harness in conformity with movements of the drop glass, and further, if somehow the power to the resistive grid could be available only when the drop glass is at the raised position (that is, prevented from being available when the drop glass is at the down position).
The present invention is an electrical connection mechanism for the resistive grid of a motor vehicle drop glass, wherein an electrical connection is established only when a grid terminal, which is affixed to the drop glass, is in contact with a gate terminal, which is affixed to the tailgate.
In a first form of the present invention, the grid terminal is located at a lower end comer of the drop glass and is electrically connected to a first buss bar of the resistive grid. The gate terminal is stationarily located inside the tailgate along a drop path of the grid terminal. In operation beginning with the drop glass at a lowered position, electrical contact between the gate terminal and the grid terminal occurs when the drop glass has moved upwardly sufficient that the grid terminal has physically slid contactingly onto the surface of the gate terminal, whereupon the resistive grid is powerable by the motor vehicle electrical system, subject to the operator engaging power thereto.
In a second form of the present invention, the gate terminal is located on a push switch which is connected to the tailgate. In operation beginning with the drop glass at a lowered position, electrical contact between the gate terminal and the grid terminal occurs when the drop glass has moved upwardly sufficient that the grid terminal has physically slid contactingly onto the surface of the gate terminal, as mentioned hereinabove. Now, however, as the grid terminal contacts the gate terminal, a lateral displacement causes the push switch (which is normally biased to OFF) to be switched ON, whereupon the resistive grid is powerable by the motor vehicle electrical system, subject to the operator engaging power thereto.
Accordingly, it is an object of the present invention to provide an electrical connection mechanism for connecting a resistive grid of a drop glass to a motor vehicle electrical system without the necessity of a flexible wiring harness which accommodates drop glass up and down movements.
It is an additional object of the present invention to provide an electrical connection mechanism for connecting a resistive grid of a drop glass to a motor vehicle electrical system without the necessity of a flexible wiring harness which accommodates drop glass up and down movements, wherein power is supplied to the resistive grid only when the drop glass is at the raised position.
These and additional objects, features and advantages of the present invention will become clearer from the following specification of a preferred embodiment.